Process of preventing scale and deposit formation in aqueous systems and compositions

ABSTRACT

SCALE FORMATION AS WELL AS DEPOSITION OF INCRUSTATIONS IN AQUEOUS SYSTEM ARE PREVENTED BY THE ADDITION OF A COMPOSITION CONTACTING STARCH DEGRADATION PRODUCTS AND PHOSPHORIC ACIDS, PREFERABLY IN SUBSTOICHIOMETRIC AMOUNTS CALCULATED FOR THE SCALE AND HARDNESS CAUSING COMPOUNDS PRESENT IN AQUEOUS SYSTEMS. ACRYLIC ACID AND/OR METHACRYLIC ACID POLYMERS OR COPOLYMERS WITH POLYMERIZABLE ETHYLENICALLY UNSATURATED COMPOUNDS MAY ALSO BE ADDED.

United States Patent O1 PROCESS OF PREVENTING SCALE AND DEPOSITFORMATION .IN AQUEOUS SYSTEMS AND COMPOSITIONS Friedrich Krueger,Edingen, and Lieselotte Bauer, Bad Duerkheim, Germany, assignors to-Joh. A. Benckiser GmbH, Chemische Fabrik, Ludwigshafen am Rhine, GermanyNo Drawing. Continuation-impart of abandoned application Ser. No.36,403, May 11, 1970. This application Nov. 17, 1971, Ser. No. 199,792

Claims priority, application Germany, Nov. 20, 1970, P 20 57 008.5 Int.Cl. C02c 5/06 U.S. Cl. 252-180 12 Claims ABSTRACT OF THE DISCLOSUREScale formation as well as deposition of incrustations in aqueoussystems are prevented by the addition of a composition containing starchdegradation products and phosphonic acids, preferably insubstoichiometric amounts calculated for the scale and hardness causingcompounds present in aqueous systems. Acrylic acid and/or methacrylicacid polymers or copolymers with polymerizable ethylenically unsaturatedcompounds may also be added.

CROSS-REFERENCE TO RELATED APPLICATION The present application is acontinuation-in-part of copending application Ser. No. 36,403, filed May11, 1970, and entitled Process of Preventing Scale Formation in AqueousSystems, and Product, now abandoned.

BACKGROUND OF THE INVENTION (1) Field of the invention The presentinvention relates to an improved process of preventing scale and depositformation in aqueous systems and more particularly to a process ofpreventing such scale and deposit formation in aqueous systems by meansof compositions containing starch degradation products and phosphonicacids, which are added in small amounts to the aqueous system, and tocompositions useful in such a process.

(2) Description of the prior art Polyphosphates are used extensively forpreventing scale and deposit formation in aqueous systems. Thepolyphosphates are added mainly for the reason that they are effectivein sub-stoichiometric, so-called threshold amounts and that they arerelatively inexpensive. It is, however, known that the olyphosphates arehydrolyzed in aqueous solutions under certain conditions. Thus theamounts of olyphosphates to be added are sometimes quite high and theireffectiveness is frequently not fully satisfactory.

Recently phosphonic acids have become of ever increasing importance foruse as complexing, sequestering compounds because they are stable inaqueous solution for an almost indefinite period of time and preventscale and deposit formation in sub-stoichiometric amounts. They areadded to aqueous systems mainly on account of their stability tohydrolysis. For this reason they are admixed, for instance, to cleaningand rinsing solutions in which they are stable for a prolonged period oftime even under the most varied conditions of use and storage. Thephosphonic acids, however, have the disadvantage that, in contrast tothe olyphosphates, they are relatively expensive due to the costlystarting materials used in their manufacture.

According to U.S. Pat. No. 3,354,094 starch degradation products, forinstance, dextrins, obtained by roasting, i.e. by a heat treatment ofstarch in the absence of moisture ice at a temperature between C. and200 C., are capable of preventing or suppressing scale formation.

Furthermore it has been found that modified starch obtained on treatingstarch with acids or exposing it to the action of oxidizing agents belowthe glutinization temperature, has a satisfactory seeding or solubilityinducing effect. Such modified starches are obtained thereby in solidform. They are insoluble in cold water and must be boiled in waterbefore use in order to produce the required solutions. The preparationof such modified starch solutions by boiling in water, however, israther complicated and frequently cannot be carried out by the users ofsuch starch products for preventing scale formation.

It is also known from French Pat. No. 1,556,011 to add backing sirupcontaining dextrins to rinsing agents.

All these known compositions and processes, however, have disadvantagesand/or are rather expensive.

SUMMARY OF THE INVENTION It is one object of the present invention toprovide a simple and highly effective process of preventing orsuppressing scale formation in aqueous systems which process is free ofthe disadvantages of the heretofore used processes.

Another object of the present invention is to provide highly effective,rather inexpensive, scale formation preventing or suppressingcompositions which are added to aqueous systems in sub-stoichiometric,i.e. seeding or solubility inducing amounts.

Still another object of the present invention is to provide scaleformation preventing or suppressing acid, for alkaline cleaning orrinsing solutions which are useful, for instance, in bottle rinsingmachines, for cleaning and rinsing milk cans, and for other cleaning andrinsing operations.

Other objects of the present invention and advantageous features thereofwill become apparent as description proceeds.

According to the present invention a synergistic effect which farexceeds the effect of the scale formation preventing or suppressingagents when used each one separately, is achieved by adding to aqueoussystems a composition consisting (a) of starch degradation products suchas dextrins which are produced, for instance, by roasting starch in theabsence of moisture at a temperature between 150 C.

and 200 C., and/or by heating starch in aqueous mineral acid solutionsat a temperature exceeding 50 C., and especially of starch degradationproducts which are readily soluble in water, and (b) of amino alkylenephosphonic acids and/ or hydroxy or amino alkane phosphonic acidswherein such starch degradation products and phosphonic acids arepresent in a proportion, by weight, between 1:1 and 50:1 and preferablybetween 2:1 and 20:1.

The concentration in which the two active agents according to thepresent invention are added to the aqueous systems may amount to 500mg./l. of water and is preferably between 10 mg./l. and 30 mg./l. ofwater.

Dextrins which have proved to be useful for the purpose of the presentinvention are, for instance, the solid dextrins obtained by roastingstarch as they are described in Ullmanns Enzyklopaedie der technischenChernie, 3rd edition, volume 16, pages 349 to 352; likewise the whitedextrins obtained by heating starch in the absence of moisture to atemperature between 150 C. and 200 C., or the yellow dextrins producedon roasting starch which had been pretreated with a small amount ofacid; or starch degradation products which are soluble in cold water.Such and other starch degradation products, i.e. dextrins are obtained,for instance, according to U.S. Pat. No. 3,354,094.

Especially useful starch degradation products can be produced by addingoxidizing agents to aqueous starch suspensions below the glutinizationtemperature and subsequently heating the mixture to a temperature notsubstantially exceeding 100 C. According to a modification of thisprocess the oxidizing agent is added to the aqueous starch suspension ata temperature above the glutinization temperature, whereafter themixture is kept at the reaction temperature until the starch has becomesoluble. If desired, the resulting aqueous solution is then evaporatedto dryness. For instance, a 20% to 40% suspension of starch in water isprepared, the oxidizing agent is slowly added thereto at roomtemperature within half an hour to two hours while stirring, and theresulting mixture is then heated to a temperature between about 60 C.and about 100 C. for several hours.

One may also proceed by first causing glutinization of the starch byheating the starch suspension to a temperature above 50 C. whereafterthe oxidizing agent is added to the glutinized starch suspension.Heating of the resulting mixture is continued until the starch hasbecome soluble. When proceeding in this manner, it is advisable to startwith a 5% to 15% starch suspension because otherwise the starch pastebecomes too viscous and cannot be stirred properly at the time theoxidizing agent is added.

It is, of course, also possible first to add only part of the oxidizingagent at room temperature to the aqueous starch suspension and to admixthe remainder during heat ing to a temperature above 50 C. or after saidtemperature has been reached.

Especially suitable oxidizing agents are alkali metal hypochlorites,such as sodium hypochlorite, or hydrogen peroxide. The oxidizing agentsare preferably added in aqueous solution in amounts between about 1% toabout 25% calculated for the starch.

Clear aqueous solutions of starch degradation products are obtained inthis manner. These starch solutions are resistant to hydrolysis and canbe stored for a prolonged period of time. They can be diluted with waterand can be adjusted, as required, to acid, alkaline, or neutral reactionwithout disadvantageously alfecting their properties and scale formationsuppressing activity. It is also possible to isolate the active starchdegradation products in solid form by either evaporating the aqueoussolution in a vacuum to dryness or by passing it over a roller dryer.Thereby the active starch degradation product is obtained in the form ofa porous material which can readily be pulverized and which is solublein cold water without lump formation.

The dextrins according to the present invention can be produced from anykind of starch such as potato starch, corn starch, and others.

An especially high synergistic effect of compositions according to thepresent invention is achieved by using, in mixture with phosphonicacids, glucose sirups or starch sirups as they are described, forinstance, in Ullmanns Encyclopaedie der technischen Chemie, 3rd edition,volume 9, page 659. Such glucose sirups are produced by heating starchwith water and a small amount of a mineral acid above the glutinizationtemperature. They are composed of a mixture of dextrin, glucose, andmaltose. The content of reducing substance in said mixture expressed asdextrose units=DU (see Ullmanns Encyclopaedie der technischen Chemie,3rd edition, volume 16, page 326) can be greater or smaller dependingupon the reaction conditions. Such glucose sirups are commerciallyavailable in the form of 80% sirups, calculated for its solids content.It is, of course, understood that such glucose sirups can be producedfrom any kind of starch, such as potato starch, corn starch, waxycornstarch, and others. Preferably sirups of 20 to 60 dextrose units areused.

Phosphonic acids which are especially useful for the purpose of thepresent invention are amino alkylene phosphonic acids of the followingformulas:

FORMULA I In said formula R represents the group of the formula 0HCHz-P0 and R represents either (a) the group of the formula (b) thegroup of the formula OH CI12-P0 LIIM .Jy Rz wherein R and R (1) bothrepresent the group of the formula 0H ..CH -P0 (2) one of R and R ishydrogen and the other one is the group of the formula (3) both arehydrogen; while x is one of the numerals 2 and 3, and y is one of thenumerals from 0 to 4; or

(c) the group of the formula OH -CH2P O ;01

(d) the group of the formula 0H (Ill -P40 (CHz)mS(CHa)nN OH OH GHQ-P40wherein m and n are the numerals l to 3.

Examples of amino alkylene phosphonic acids which have proved to'beuseful in the process according to the present invention are, forinstance,

FORMULA II H Ra H wherein R is hydrogen, hydroxyl, an amino, loweralkylamino or di-lower alkylamino group, or lower alkyl with 1 to 8carbon atoms,

R, is hydrogen or lower alkyl with 1 to 10 carbon atoms which may besubstituted by the group Such compounds are, for instance,

l-hydroxy ethane-1,1-diphosphonic acid, l-amino ethane-1,1-diphosphonicacid, l-hydroxy ethane-1,1,2-triphosphonic acid,

and others.

Mixtures of such phosphonic acids can, of course, also be used.

Acrylic acid and/ or methacrylic acid polymers or copolymers of suchacids with each other or with other polymerizable ethylenicallyunsaturated compounds can also be added to the above describedcompositions of dextrins and phosphonic acids. Polymers which haveproved to be especially suitable additives to aqueous systems incombination with said amino alkylene phosphonic acids and dextrins forpreventing scale and deposit formation are, for instance,

polymerization products obtained by polymerization of acrylic acid ormethacrylic acid, preferably of a molecular Weight of at least 500;

copolymerization products of acrylic acid and methacrylic acid;

polymers obtained by copolymerization of acrylic acid and/ ormethacrylic acid with other polymerizable ethylenically unsaturatedmonomers such as crotonic acid, maleic acid or its anhydride, vinylsulfonic acid, vinyl phosphonic acid, vinyl acetate, ethyl vinyl ether,acrylamide, ethyl acrylate, ethyl methacrylate, methacrylonitrile,

and others.

The preferred polymerization products are those which are Water solubleor at least readily dispersible in water.

Most effective copolymerization products of the above mentioned polymersare the graft polymers obtained by polymerization of acrylic acid and/ormethacrylic acid, if desired, together with other copolymerizableethylenically unsaturated monomers as mentioned hereinabove, in thepresence of a polysaccharide.

Preferred polysaccharides are preformed water solu ble polysaccharidesand their derivatives, such as starches, for instance, potato starch,corn starch, and other starches, starch ethers, water soluble celluloseethers, modified starches obtained by treating starch with acids or withoxidizing agents at a temperature below the gelatinization temperature,or starch degradation products which are soluble in cold water and areobtained by treating an aqueous starch suspension with an oxidizingagent at a temperature up to C., or dextrins produced, for instance, bytreating starch with acids followed by heating to a temperature above C.or by roasting starch at C. to 200 C.

Graft polymerization of acrylic acid, methacrylic acid and, if desired,other polymerizable ethylenically unsaturated monomers in the presenceof said polysaccharides is preferably effected by heating in a waterbath in 5% to 30% aqueous solution at 40 C. to 100 C. in the presence ofa catalyst such as ammonium peroxydisulfate, mixtures of ammoniumperoxydisulfate (NHQ S O and sodium pyrosul-fite Na S O or hydrogenperoxide.

Such three component compositions produce a highly advantageouslysynergistic, scale and deposit formation preventing and hardnessstabilizing effect. Preferably such compositions consist of 2 to 4parts, by weight, of dextrin or glucose sirup, 2 to 4 parts, by weight,of polymeric compound, and 1 part, by weight, of phosphonic acid.

As stated above, the combination of starch degradation products ordextrins, phosphonic acids and, if desired, acrylic acid and/ormethacrylic acid polymers, copolymers, and graft polymers withpolysaccharides according to the present invention are added to cleaningcompositions as they are known to the art and especially to acidic oralkaline cleaning and rinsing fluids. Of particular advantage is theaddition of such compositions to cleaning and rinsing fluids used inautomatically operating bottle cleaning and rinsing machines or incleaning tanks and other types of containers. In such cleaningoperations scale and deposit formation takes place especially at thestage when the bottles, tanks, or containers are rinsed with freshwater, i.e. at that stage of the cleaning and rinsing process when onlytraces of the cleaning agent diluted with large amounts of rinsing waterare present and are removed by rinsing. Such scale formation isprevented by the presence of small (seeding or threshold) amounts of thehardness stabilizing combination according to the present invention inthe strongly diluted rinsing water. If necessary, small amounts of thecombination according to the present invention may be added to therinsing fluids for application to those zones of the aqueous systemwhich are especially exposed to scale and deposit formation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The synergistic effect of theagents according to the present invention which exceeds the additiveeffects of the components given separately is shown in the followingtables in comparison with the threshold value of the components testedalone and not in combination with each other.

The threshold value was determined by adding to and dissolving in oneliter of water of about 15 (German degrees of hardness), Placed in aglass beaker, 12 g. of sodium hydroxide and a predetermined amount, inmg., of the compound or, respectively, the mixture of compounds 8 Thefollowing examples serve to illustrate the preparation of coldwater-soluble starch degradation products without, however, beinglimited thereto.

Example 1 200 g. of an aqueous sodium hypochlorite solution containing14.5% of reactive chlorine are slowly added drop by drop to a suspensionof 300 g. of potato starch in 500 cc. of water at 20 C. to 30 C. within2 hours TABLE I.THRESHOLD EFFECT OF STARCH DE GRADATION PRODUCTS(Component A) Amount Crystals deposited after a: days added Component Ain mg. 1 2 3 4 5 6 7 8 I Glucose sirup from yellow corn 12. 5

starch with 52 DU. IL- Glucose sirup from yellow corn 12. 5

starch with 40.6 DU. III Glucose sirup from potato 12. 5

starch with 52.3 DU. IV Glucose sirup from potato 12.5 0

starch with 37.5 DU. V Glucose sirup from waxy corn 12.5

starch with 49.2 DU. IV Glucose sirup from waxy com 12. 0

starch with 38 DU. VII Glucose sirup with 32 DU 12. 5 0 VIII Whitedextrin obtained by 12.5 0

roasting starch. IX Yellow dextrin obtained by 12. 5

roasting starch.

TABLE IL-SEEDING EFFECT OF THE PHOSPHONIC ACID while stirring.Thereafter, the starch suspension is heated to 90 C. to 100 C. Stirringat said temperature is continued for five more hours. A fluid solutionof low viscosity containing 30% of the starch degradation product isobtained. Said solution is diluted to 20% by the addition of water.

Example 2 The solution obtained according to Example 1 is evaporated todryness in a vacuum. The starch degradation product is obtained in theform of a porous powder which is readily soluble in cold water withoutformation of lumps.

TABLE III.SEEDING EFFECT OF MIXTURES OF STARCH DEGRADATION PRODUCTS ANDPHOSPHONIC ACIDS Amounts added in mg. Standing for (days)- Components Aand B oftho mixture (A) (B) 1 2 a 4 e 7 s 9 1o 11 12 7.5 2.5 0 o 0 0 0 00 0 1o 5 o 0 o 0 0 o 0 2.5 o 0 0 0 0 0 0 0 0 7.5 2.5 o 0 o 0 0 0 o 0 7.52.5 0 0 0 o 0 0 o 0 10 2.5 0 o o 0 0 0 0 o 0 0 10 2.5 o 0 o 0 0 o 0 o o10 2.5 0 o 0 0 o 0 0 o 10 2.5 0 0 0 0 0 0 0 0 10 2.5 0 0 0 0 o 0 0 0 7.52.5 0 0 0 0 0 0 0 0 10 2.5 0 o 0 0 0 0 0 10 2.5 0 0 0 o 0 0 o 0 TABLEIV.-SEEDING EFFECT OF THE POLYMERS Example 3 (Cmnpmlent C) 150 g. ofpotato starch are suspended in 250 cc. of wa- Amo m Stag g; for ter. 160g. of an aqueous sodium hypochlorite solution 3. y 60 containing 14.5%of reactive chlorine are added drop by COmPOnent C 111 1 2 3 4 5 drop tothe suspension within thirty minutes. The reaction h llzollyacrylllic1151 1.... 3 7) mixture is then heated in a water bath to C. and

oymet acry caci In copolymgdzapion product stirring at said temperature1s cont1nued for three more ofaerylic acid and methhours. Thereafter themixture is heated briefly to 90 C. to 100 C. The resulting solution isadded to aqueous sys- TABLE V.-SEEDING EFFECT OF A COMBINATION OF THETHREE COMPONENTS A=starcl1 degradation product plus B =phosphonic acidplus C=polymer Amounts added tems for preventing scale formation.

Example 4 A suspension of 100 g. of corn starch in 900 cc. of water isslowly heated in a water bath to 60-70 C. while stirring. 66 g. of anaqueous sodium hypochlorite solution containing 14.5 of reactivechlorine are added drop 'by drop to the resulting starch paste. Stirringat 100 C. is continued for three more hours. A clear solution with asatisfactory seeding, i.e. solubility initiating effect is obtained.

Example Example 6 50 g. of a hydrogen peroxide solution are slowly addeddrop by drop at -30 C. to a suspension of 150 g. of potato starch in 250cc. of water. The suspension is then heated in a water bath to 8090 C.Stirring at said temperature is continued for two more hours. Theresulting solution has a good seeding, i.e. solubility initiatingeifect.

Example 7 300 g. of potato starch are suspended in 500 cc. of water. 200g. of a 15% hydrogen peroxide solution are added drop by drop at roomtemperature to said suspension. The reaction mixture is then heated to60 C. and stirring at said temperature is continued for 3 more hours.The resulting solution is evaporated to dryness in a vacuum. A brownish,porous powder which is readily soluble in cold water is obtained.

EXAMPLE 8 300 g. of corn starch are suspended in 500 cc. of water. 200g. of a 15% hydrogen peroxide solution are added drop by drop to thesuspension while stirring. The suspension is then heated to 100 C. andstirring at said The starch degradation products obtained in this mannercan be used for the purpose of the present invention in the form oftheir aqueous solutions but they can also be added in solid form to theaqueous systems to be treated.

These starch degradation products exhibit a certain capability ofmasking, i.e. combining and sequestering polyvalent cations, especiallyalkaline earth metal ions. Thus they can be employed in all instancesinvolving the elimination of undesired and interfering metal ions inaqueous media such as calcium, magnesium, iron, and other ions. For thisreason they represent also useful additives to detergents and cleaningcompositions in solid or liquid form and can be used in various textilefinishing processes.

The amounts of such starch degradation products when added to hard waterin order to prevent or suppress scale formation, may be up to 500 mg./l.of water. Preferably their concentration is between about 10 mg./l. andabout 30 mg./l. of water.

The hardness reducing or suppressing effect of such starch degradationproducts according to the present invention can also be improved byusing them in mixture with phosphonic acids. The proportions, by weight,of starch degradation product to amino alkylene phosphonic acid may varybetwen about 1:1 and about :1 and is preferably between about 4:1 andabout 20:1. The amounts of such mixtures added to one liter of water maybe up to 500 mg. and are preferably between about 10 mg. and about 30mg. A synergistic scale formation suppressing effect which exceeds theadditive effect of the two agents, is achieved thereby.

The seeding, i.e. the solubility initiating effect of such starchdegradation products and especially the synergistic effect of thecombination of such starch degration products and phosphonic acids willbe demonstrated in the following Tables 6, 7, and 8.

TABLE VL-SEEDING EFFECT OF STARCH DEGRADATION PRODUCTS Amount Standingfor (days)- added Compound in g. 2 4 6 8 10 12 14 Starch degradationproduct according to Example 12 0 0 0 1. 20 0 0 0 0 0 0 Starchdegradation product according to Example 10 0 0 0 2. 20 0 0 0 0 0 0Starch degradation product according to Example 10 0 0 0 20 0 0 0 0 0 00 Starch degradation product according to Example 10 0 0 0 4. 20 0 0 0 00 Starch degradation product according to Example 12. 5 0 0 0 0 5. 20 00 0 0 0 Starch degradation product according to Example 12.5 0 0 0 0 0Starch de r dation roduct accordin to Example 10 0 0 0 7. g a p g 20 0 00 0 0 0 St hd radatlon roduct aceordin to Example 10 0 0 0 gm eg D g 200 0 0 0 0 Untreated potato starch 30 temperature is continued for twomore hours. After evapcrating the resulting solution to dryness, abrownish powder which dissolves readily in cold water without lumpformation, is obtained.

In place of potato starch and corn starch as used in the precedingexamples, there may be employed as starting materials other types ofstarch such as 'wheat starch, rice starch, tapioca starch, sago starch,waxy corn starch, and others.

TABLE VII.SEEDING EFFECT OF AMINO ALKYLENE PHOSPHONIC ACID acid) =ATMP.

TABLE VIII.SEEDING EFFECT OF MIXTURES OF STARCH DEGRADA- TION PRODUCTSAND AMINO ALKYLENE PHOSPHONIC ACIDS Amounts Components of the mixtureadded in mg. 2 4

Standing for (days) Starch degradation product according to:

ETPMP Example 3 Example 3 plus EDTMP. Example 8 plus EDTMP--- Example 8plus DETPMP" The tested compounds and mixtures as mentioned in thepreceding Tables I to VIII exhibit the same excellent scale formationsuppressing effect at the pH-value of the water, i.e. without additionof alkali metal hydroxide. The foregoing tests, however, were carriedout at an alkaline pH-value in order to demonstrate the advantageouseffect of the compositions according to the present invention in such analkaline medium as it is encountered in many rinsing and cleaningoperations and preparations.

As stated above and is evident from Tables III, V, and VIII, thecombinations of starch degradation products and phosphonic acids or ofstarch degradation products, phosphonic acids, and polymers have aconsiderably better efiect than the components when added alone, saidelfect exceeding the additive effect of the components.

Addition of the compounds according to the present invention or theirmixtures to acid or alkaline cleaning solutions have proved particularlyuseful. It is especially advantageous to use said compounds andmixtures, for instance, in automatically operating bottle rinsingmachines or for cleaning tanks or containers. In such operations scaleformation takes place quite readily especially at the stage whereby thebottles, tanks, or containers are subsequently rinsed with fresh water,i.e. at that stage of the rinsing and cleaning process when only tracesof the cleaning agent diluted with large amounts of water are presentand are washed out thereby. Such scale formation is prevented by thepresence of smallest (seeding or solubility initiating) amounts of thecompounds according to this invention in the highly diluted rinsingwater. If necessary, small amounts of the compounds according to thepresent invention may be added to the rinsing solutions for applicationto those zones which are especially exposed to scale formation.

The following examples describe suitable cleaning and rinsing solutionsaccording to the present invention without, however, being limitedthereto.

Example 9 The composition contains 40% of acid phosphoric acid alkylesters with 2 to 3 carbon atoms in the alkyl ester group, 20% of amixture of the starch degradation product of Example 1 and diethylenetriamino penta- (methylene phosphonic acid) (:2.5), 10% of theantifoaming agent Pluronic L 21 (Wyandotte) and 30% of water.

0.3% of said composition are added to an aqueous 1% sodium hydroxidesolution. The resulting cleaning solution is an excellent bottle rinsingsolution.

Example 10 The composition contains 50% of an aqueous 67% gluconic acidsolution, of the starch degradation product of Example 3 and 30% ofwater.

0.2% of said mixture are added to an aqueous 1% sodium hydroxidesolution to yield a highly effective bottle rinsing solution.

Example 11 The composition contains 35% of sodium silicate, 3% of thestarch degradation product of Example 6, 20% of sodium carbonate, 17% ofsodium hydroxide, 5% of the wetting agent Arkopal N/O 60 (Hoechst), 10%of sodium sulfate, and 10% trisodium orthophosphate.

1% aqueous solutions of said composition are advantageously used forcleaning and rinsing milk cans.

Example 12 The composition contains 40% of tripolyphosphate, 10% of thestarch degradation product of Example 8, 5% of the antifoaming agentPluronic L 21 (Wyandotte), 10% of trisodium orthophosphate, and 35 ofsodium gluconate.

0.2% of said composition are added to 1.5% aqueous sodium hydroxidesolution. The resulting solution has proved useful for cleaning andrinsing of bottles and especially for cleaning bottles provided withlabels and/or caps made of aluminum.

Example 13 The composition contains 40% of a mixture of phosphoric acidmonoand dimethyl ester, 20% of a mixture of glucose sirup obtained fromyellow corn starch with 52 DU and of nitrilo tris-(methylene phosphonicacid) in the proportion of 4:1, and 40% of water.

0.3% of said composition are added to an aqueous 1% sodium hydroxidesolution. The resulting cleaning solution is an excellent bottle rinsingsolution.

Example 14 The composition contains 40% of the acid methyl isopropylester of phosphoric acid, 20% of a mixture of glucose sirup obtainedfrom waxy corn starch with 38 DU and diethylene triamino penta-(methylene phosphonic acid) in the proportion of 3:1, and 40% of water.

0.2% of said mixture are dissolved in a 1% sodium hydroxide solution.The resulting solution is used for rinsing bottles.

Example 15 The composition contains 70% of a 67% gluconic acid solution,20% of a mixture of glucose sirup obtained from potato starch with 32 DUand nitrilo tris- (methylene phosphonic acid) in the proportion of 3:1,and 10% of water.

0.2% of said mixture are dissolved in 1% sodium hydroxide solution. Thesolution is a highly elfective bottle rinsing solution.

Example 16 Example 17.-Polyacrylic acid Example 18.-Polymethacrylic acidA solution of 19.2 g. of ammonium persulfate in 1120 cc. of water isheated on a boiling water bath. 480 g. of methacrylic acid are addedthereto within 20 minutes, while stirring. Subsequently the mixture isheated for one more hour and is then cooled. It is directly used asdescribed in Example 17.

Example l9.Copolymerization product of acrylic acid and methacrylicacid 1) 50 g. of monomeric acrylic acid and g. of monomeric methacrylicacid are added drop by drop to a solution of 2.4 g. of ammoniumpersulfate in 240 cc. of water which has been heated on a boiling waterbath, within about 2.0 minutes while stirring. Subsequently the mixtureis heated on the boiling water bath for one more hour and is thencooled. The resulting solution is used as described in Example 17.

Example 20.-Copolymerization product of acrylic acid and ethyl vinylether (2:1)

A solution of 2.4 g. of ammonium persulfate and 140 cc. of water isheated on a boiling water bath. 40 g. of monomeric acrylic acid and g.of ethyl vinyl other are added drop by drop thereto within about twohours. Thereafter the mixture is heated for one more hour. The resultingsolution is used as described in Example 17.

Example 21.-Copolymerization product of acrylic acid and maleic acidanhydride (2:1)

57.6 g. of ammonium persulfate in 3360 cc. of water are heated in aboiling water bath. A solution of 480 g. of maleic acid anhydride and960 g. of acrylic acid which solution has been gently heated, is addedthereto within about 2 hours. The mixture is heated for two more hours.The solution is directly used as described in Example 17.

Example '22.Copolymerization product of acrylic acid and of the sodiumsalt of vinyl sulfonic acid (2:1)

2.4 g. of ammonium persulfate are dissolved in 140 cc. of water whileheating in a boiling water bath. A mixture of 40 g. of acrylic acid and40 g. of the sodium salt of vinyl sulfonic acid (50% aqueous solution)is added thereto within about two hours. Subsequently the mixture isheated for one more hour and is then cooled and used as described inExample 17.

Example 23.Copolymerization product of acrylic acid and acrylic acidethyl ester (5: 1)

A solution of 2.4 g. of ammonium persulfate and 140 cc. of water isheated on a boiling water bath. A mixture of 50 g. of acrylic acid and10 g. of acrylic acid ethyl ester is added thereto within about twohours. Subsequently the mixture is heated for one more hour. Theresulting solution is used as described in Example 17.

Example 24.-Copolymerization product of acrylic acid and vinyl acetate(3:1)

19.2 g. of ammonium persulfate are heated in 1120 cc. of water on aboiling water bath. A-mixture of 160 g. of vinyl acetate and 320 g. ofacrylic acid is added thereto within about two hours. Subsequently themixture is heated for one more hour. After cooling, the resultingsolution 14 is used for the purpose of the present invention asdescribed in Example 17.

The terms seeding amounts, solubility inducing amounts,sub-stoichiometric amount, sub-sequestering amounts, solubilityinitiating amounts are used in the foregoing description of theinvention and in the claims in order to designate amounts of the scaleformation suppressing agents which are lower than required tostoichiometrically combine with the scale and hardness forming compoundsof the aqueous systems to be treated. Such amounts may also bedesignated as threshold amounts.

The term glutinization temperature as used in the foregoing descriptionand in the claims indicates the temperature at which gelatinization ofthe starch takes place. The glutinization temperature, i.e. thegelatinization temperature of potato starch is, for instance, 61.5 C.,that of corn starch 68.5 C., that of rice starch 75 C., that of wheatstarch 65 C. The highest temperature to be used in the production ofstarch degradation products with oxidizing agents is about 100 C., thepreferred temperatures are temperatures between about C. and about C.

The antifoaming agent Pl-uronic L 21 used in Examples 9 and 12 is a bulkcopolymer of ethylene oxide and polypropylene glycol.

The wetting agent Arkopal N/O 60 used in Example 11 is a nonylphenolpolyglycol ether with 6 moles of ethylene oxide for one mole ofnonylphenol.

Of course, other suitable antifoaming and wetting agents may also beused.

The term starch degradation products as used herein and in the claimsdefines such degradation products of starch which have been obtained bythermal, oxidative, or acid degradation or modification in order toimprove their solubility, to lower the viscosity of their aqueoussolutions, to increase their solubility in cold water, withoutcompletely hydrolyzing the starch to sugars. This term comprises amongothers the dextrins, the starch syrups, the modified starches as theyare described, for instance, by Kirk-Othmer Encyclopedia of ChemicalTechnology, second edition, vol. 18, under Starch and vol. 6 underDextrose and Starch Syrups and in Ullmanns Enzyklopaedie der technischenChemie, 3rd edition, vol. 16 under Staerke and vol. 9 underKohlenhydrate.

We claim:

'1. A composition for suppressing scale and deposit formation in aqueoussystems, said composition containing, as scale and deposit formationsuppressing agent, a mixture composed of (a) a starch degradationproduct selected from the group consisting of a dextrin produced byroasting starch and a glucose syrup, and

(b) an alkylene phosphonic acid, the starch degradation product and thealkylene phosphonic acid being present in said mixture in theproportion, by weight, between about 2:1 and about 4:1.

2. The composition of claim 1, wherein the starch degradation product isa dextrin produced by roasting starch.

3. The composition of claim 1, wherein the starch degradation product isa dextrin produced by heating to a temperature exceeding 50 C. of starchin an aqueous mineral acid solution.

4. The composition of claim 1, wherein the starch degradation product isglucose sirup.

5. The composition of claim 1, wherein the starch degradation product isa yellow dextrin.

6. The composition of claim 1, wherein the starch degradation product isa white dextrin.

7. The composition of claim 1, wherein the alkylene phosphonic acid isan amino alkylene phosphonic acid.

8. The composition of claim 1, wherein the alkylene phosphonic acid isan alkylene phosphonic acid selected from the group consisting ofdiethylene triamino penta- (methylene phosphonic acid), ethylene diaminotetra- (methylene phosphonic acid), nitrilo tris-(methylene phosphonicacid), and l-hydroxy ethane 1,1-diphsphonic acid, and mixtures thereof.

9. The composition of claim 1, additionally containing a polymerselected from the group consisting of a polymer of acrylic acid, apolymer of methacrylic acid, a copolymer of acrylic acid and methacrylicacid, a copolymer of acrylic acid and/or methacrylic acid with apolymerizable, ethylenically unsaturated compound, a graft polymer of apolysaccharide and said acrylic acid and/or methacrylic acid, and agraft polymer of a polysaccharide and said acrylic acid and/ormethacrylic acid and a polymerizable, ethylenically unsaturatedcompound.

10. A cleaning fluid comprising an aqueous cleaning solution containing,as scale and deposit formation suppressing agent, a compositioncontaining a mixture composed of (a) a starch degradation productselected from the group consisting of a dextrin produced by roastingstarch and a glucose syrup, and

(b) an alkylene phosphonic acid, the starch degradation product and thealkylene phosphonic acid being present in said mixture in theproportion, by weight, between about 2:1 and about 4:1, said compositionbeing present in said cleaning fluid in an amount between about 10mg./l. and about 500 mg./l. of cleaning fluid.

11. The cleaning fluid of claim 10 containing the composition in saidcleaning fluid in an amount between about 10 mg. /l. and about mg. /l.of cleaning fluid.

12. The cleaning fluid of claim 10 wherein the aqueous cleaning solutionis a dilute aqueous sodium hydroxide solution.

References Cited UNITED STATES PATENTS 3,575,868 4/1971 Galvin et al.252--181 3,354,094 11/1967 Brink et al. 252 3,596,766 8/1971 Johnston etal. 2l058 2,826,552 3/1958 Bonewitz et al. 252-156 3,082,173 3/1963Horvitz 252181 3,619,427 11/1971 Kautsky 2l058 3,620,974 11/1971Stanford et al. 252-855 B 3,677,956 7/1972 Carlson 252180 3,477,95611/1969 Stanford et al. 252-8.55 2,220,950 11/1940 Bird 2l023 2,382,2628/1945 Scherer et al. 252-173 3,499,842 3/ 1970 Carlson 252-1803,714,066 1/1973 King et a1 252-389 A 3,714,067 1/1973 King et al.252-389 A GEORGE F. LESMES, Primary Examiner W. R. DIXON, JR., AssistantExaminer US. Cl. X.R.

222330 U NI'I ED STATES PATENT OFFICE CERTIFICATE OF CORRECTIQN PatentNo. 3 {7913978 7 Dated February 12 1974 Inventor) Friedrich Krueger andLieselotte Bauer It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 2, line 30: Change for" to or Column 2, line 35: Before"description" insert the Signed and' sealed this 14th, day of June 1974.

(SEAL) Attest:

C MARSHALL DANN Commissioner of Patents.

EDWARD M.FLETCHER,JR. Atteating Officer

